Preparation,Characterization And Application Of The Functional Materials Of Extract Of Apple Pomace And Hyperbranched Polyethyleneimine

In order to accomplish the reuse of the waste biomass material apple pomace(AP)and modify the cellulose(CF)extracted from AP,this paper aims to explore its application potential in the field of adsorption and catalysis.Two kinds of cellulose derivatives were prepared and adsorbed and catalyzed respectively.The main contents are as follows:1.Dialdehyde cellulose(DAC)was successfully prepared by oxidizing cellulose extracted from AP with sodium periodate.Under the conditions,the content of aldehyde of DAC prepared by sodium periodate oxidation system was up to 9.2 mmol/g.It was confirmed by FTIR spectra that the secondary hydroxyl groups of glucose units of cellulose were successfully oxidized and the aldehyde group mainly existed in the form of hemiacetal.In addition,it was found the crystalline type of oxidized cellulose changed,crystallinity and heat resistance decreased from the thermogravimetric data and the X-ray spectra.Due to changes in the chemical and physical properties of cellulose by oxidation reaction,the application basis of DAC had been laid.2.The HPEI-DAC functional material was prepared by grafting hyperbranched polyethyleneimine(HPEI)onto the DAC via Schiff base reaction.The FTIR and XPS spectra indicated that HPEI-DAC were successfully prepared.HPEI-DAC was used to adsorb methyl orange(MO)in water.HPEI-DAC was used to adsorb methyl orange(MO)in water,and the effects of the MO concentration,the dosage of adsorbent,pH,temperature and time on adsorption performance were investigated.At 25℃,the adsorption data accords with the Langmuir isotherm adsorption model.The maximum theoretical amount of MO on HPEI-DAC was 280.98 mg/g,and the adsorption capacity of HPEI-DAC can still keep over 70%of the initial adsorption after 6 regenerations.Therefore,HPEI-DAC is a promising adsorbent in the treatment of azo dye wastewater.3.AuNPs-HPEI-DAC was prepared by in situ reduction of chloroauric acid using HPEI-DAC as carrier and reducing agent.TEM showed that the particle size of AuNPs were approximately 7 nm.The effects of temperature,amount of catalyst and concentration of p-nitrophenol on the catalytic reaction were investigated through catalytic reduction of nitrophenol by AuNPs-HPEI-DAC as the research object.AuNPs-HPEI-DAC can still complete the catalytic reduction reaction within 114 min after 7 times of catalytic applications.The results show that the high catalytic efficiency and good reusability of AuNPs-HPEI-DAC are of great value for the treatment of organic phenolic compounds in wastewater.